Autofocus camera and camera-equipped electronic device

ABSTRACT

An autofocus camera is provided which restrains and corrects any tilt that may occur in the optical axis direction without the need of providing any additional new sensors for that purpose. The autofocus camera includes an image sensor for receiving light from an object and converting the light into corresponding electrical signals, a lens driving device having a lens for focusing the light from the object upon said image sensor, and a control portion for causing said lens driving device to adjust any tilt that may occur in the optical axis in response to the electrical signals received from said image sensor. The control portion is operated to cause the lens driving device to adjust any tilts of the optical axis with respect to the image sensor in the orthogonal directions with each other, so that the resolution signals at the predetermined positions of said image sensor can be maximized.

BACKGROUND OF T HE INVENTION

1. Field of the Invention

The present invention relates to an autofocus camera mounted on anelectronic device such as mobile phones and the like, and acamera-equipped electronic device.

2. Description of Relevant Art

For the conventional autofocus camera, there is an important problem inthat any tilt that may occur in the camera's optical axis must berestrained and corrected in order to meet the needs of achieving thehigh picture elements and the like.

There have been various proposals that attempt to solve the aboveproblem. In Patent Document 1, for example, it is proposed that thesensor that detects any tilt that may occur in the optical axis of thelens is to be attached to a lens support. The sensor attached to thelens support is so designed that any tilt that may occur in the opticalaxis can be restrained and corrected on the realtime basis by allowingit to detect any tilt of the lens support.

Patent Document 1: WO2011/021502A1

SUMMARY

The structure proposed by Patent Document 1 requires that any additionalnew sensors and wires are to be added. This presents a problem in thatthe lens driving device must be made smaller.

In light of the above problem, the object of the present invention is toprovide an autofocus camera that is capable of restraining andcorrecting any tilt and a camera-equipped electronic device without theneeds of adding any additional new sensors.

The invention according to claim 1 provides an autofocus cameracomprising:

an image sensor for receiving light from an object and converting thelight into corresponding electrical signals;

a lens driving device having a lens for focusing the light from theobject upon said image sensor; and

a control portion for causing said lens driving device to adjust anytilt that may occur in the optical axis in response to the electricalsignals received from said image sensor, wherein said control portion isoperated to cause said lens driving device to adjust any tilts of theoptical axis with respect to the image sensor in the orthogonaldirections with each other, so that the resolution signals at thepredetermined positions of said image sensor can be maximized.

The invention according to Claim 2 provides the autofocus camera asdefined in Claim 1, wherein said resolution signals are derived fromeither of the center area of said image sensor and the peripheral areasof said image sensor.

The invention according to Claim 3 provides the autofocus camera asdefined in Claim 1, wherein said control portion is operated todetermine an average value obtained by averaging said resolution signalsobtained at more than one point of said image sensor and adjust anytilts of the optical axis with respect to the image sensor in theorthogonal directions with each other, so that said average value can bemaximized.

The invention according to Claim 4 provides an electronic device onwhich the autofocus camera as defined in any one of Claims 1 through 3is mounted.

As one advantage of the present invention, it can provide an autofocuscamera that is capable of restraining and correcting any tilt and acamera-equipped electronic device without the needs of adding anyadditional new sensors.

DESCRIPTION OF THE DRAWINGS

FIG. 1( a), (b) is a concept diagram that is used to explain how anytile that may occur can be detected in accordance with an embodiment ofthe present invention;

FIG. 2 is an exploded perspective view of one form of the lens drivingdevice employed in the camera of an embodiment of the present invention;

FIG. 3 is a partly cross-sectional perspective view of the one form ofthe lens driving device employed in the camera of an embodiment of thepresent invention;

FIG. 4 is a block diagram illustrating the relationship between the lenssupport and the control portion in the one form of the lens drivingdevice employed in the camera of an embodiment of the present invention;

FIG. 5 is an exploded perspective view of another form of the lensdriving device employed in the camera of an embodiment of the presentinvention;

FIG. 6 is a partly cross-sectional perspective view of the other form ofthe lens driving device employed in the camera of an embodiment of thepresent invention;

FIG. 7 is a block diagram illustrating the relationship between the lenssupport and the control portion in the other form of the lens drivingdevice employed in the camera of an embodiment of the present invention;

FIG. 8 is a flow diagram that explains one example of the tiltcorrection that is performed in the camera of an embodiment of thepresent invention;

FIG. 9 is a flow diagram that is used to explain the steps that arepreformed following the tilt correcting steps in FIG. 8; and

FIG. 10 is a diagram that is used to explain the positions where thecorresponding resolution signals can be derived for correcting any tiltthat may occur in the optical axis with respect to the image sensor, inwhich (a) represents the center area where the image sensor is located,(b) represents the position of the image sensor that corresponds to theposition of the human face as recognized, and (c) represents the centerarea and peripheral areas of the image sensor where the correspondingresolution signals are derived.

BEST MODES OF EMBODYING THE INVENTION

The present invention can be applied to the autofocus camera that may beincorporated in the lens driving device.

By referring first to FIG. 2 through FIG. 4 in the accompanyingdrawings, one example of the lens driving device that is employed in thecamera of the present invention will be described.

The lens driving device 1 shown in FIG. 2 through FIG. 4 is the lensdriving device for the autofocus camera that may be incorporated in anytype of mobile phone or multifunction mobile phone, for example. For theconvenience of description, the side on which an object is located willbe referred to as the front side and the side on which the image sensor31 is located will be referred to as the rear side when those sides areviewed from the lens driving device 1.

The lens driving device 1 shown in FIGS. 2 and 3 includes a yoke 3, alens support 5, a frame 7, a base 8, a front side spring 9, a rear sidespring 11, a front side spacer 14, and a rear side spacer 15.

In the example shown, the yoke 3 has the annular shape, and is fixedlydisposed between the base 8 and the frame 7. The frame 7 and the frontside spring 9 are arranged on the front side of the yoke 3 in theoptical axis direction thereof, while the base 8 and the rear sidespring 11 are arranged on the rear side of the yoke in the optical axisdirection thereof. The front side spacer 14 is arranged between thefront side spring 9 and the yoke 3, and the rear side spacer 15 isarranged between the rear side spring 11 and the yoke 3.

As shown in FIG. 3, the front side spring 9 has the flat plate shape inits original form (FIG. 2) in which it is not yet mounted as shown inFIG. 3. The front side spring 9 includes an outer circumferentialportion 9 a, an inner circumferential portion 9 b located inside theouter circumferential portion 9 a, and each of the arm portions 9 clinking the outer circumferential portion 9 a and the innercircumferential portion 9 b. In the example shown, the outercircumferential portion 9 a has the annular shape in the rectangularform as it is viewed in plane, and the inner circumferential portion 9 bhas the arc shape as it is viewed in plane.

Similarly, the rear side spring 11 has the flat plate shape in itsoriginal form (FIG. 2) in which it is not yet mounted as shown in FIG.3. The rear side spring 11 includes an outer circumferential portion 11a, an inner circumferential portion 11 b located inside the outercircumferential portion 11 b, and each of the arm portions 11 c linkingthe outer circumferential portion 11 a and the inner circumferentialportion 11 b. In the example shown, the outer circumferential portion 11a has the annular shape in the rectangular form as it is view in plane,and the inner circumferential portion 11 b has the arc shape when it isview in plane.

In the example shown, the yoke 3 has the substantially square tubularshape. The yoke 3 has four corners, to each of which a correspondingfront side magnet 17 a and a corresponding rear side magnet 17 b arefixed on the inner circumferential side thereof. In the specification,the four front side magnets 17 a and the four rear side magnets 17 b maybe referred to collectively as the magnets 17.

It may be apparent from the example shown that each of the front sidemagnets 17 a and each of the rear side magnets 17 b has thesubstantially triangular shape as it is viewed from its front side. Itmay also be apparent from the example shown that while the lens support5 has the substantially cylindrical shape, each of the front sidemagnets 17 a and each of the rear side magnets 17 b has its innercircumferential side formed like the substantially arc shape thatcorresponds to the cylindrical shape of the lens support along the outercircumference of the lens support 5.

As shown in FIG. 3, each of the front side magnets 17 a has its innercircumferential side that provides one polarity while each of the rearside magnets 17 b has its inner circumferential side that provides theopposite polarity.

As it is apparent from the example shown, each of the four front sidemagnets 17 a has its inner circumferential side that provides the Npolarity and its outer circumferential side that provides the Spolarity, while each of the four rear side magnets 17 b has it innercircumferential side that provides the S polarity and its outercircumferential side that provides the N polarity.

In the example shown, the lens support 5 has the substantiallycylindrical shape, and a lens (not shown) is fixed to the innercircumferential side of the lens support 5.

The lens support 5 has four projections 5 a on its outer circumferentialsurface that extend toward the outer circumferential side thereof, thosefour projections 5 a being provided at regular intervals in thecircumferential direction.

The lens (not shown) fixed to the inner circumferential side of the lenssupport 5 receives light from an object located on the front side inFIG. 2, and causes the light to be focused upon the image sensor 31, thedetails of which will be described later.

The lens support 5 has a first coil 16 on its outer circumferentialsurface, the first coil 16 including a coil wound in the circumferentialdirection. As shown in FIG. 2, the first coil 16 includes a front sideportion 16 a and a rear side portion 16 b which are separated from eachother in the forward and backward directions. The coil in the front sideportion 16 a and the coil in the rear side portion 16 b are wound in therespective directions opposed to each other, and are connected to eachother.

The front side portion 16 a and the rear side portion 16 b that areincluded in the first coil 16 are separated from each other by means ofthe four projections 5 a provided on the outer circumferential surfaceof the lens support 5.

As shown in FIG. 2 and FIG. 3, four second coils 19 a, 19 b, 19 c and 19d are provided on the outer circumferential surface of the first coil 16disposed on the outer circumferential surface of the lens support 5 sothat they can be placed over the first coil 16. The second coils 19 a,19 b, 19 c and 19 d are mounted at equal intervals in thecircumferential direction. Each of the second coils 19 a, 19 b, 19 c and19 d has the annular shape as it is viewed from its lateral side asshown in FIG. 2.

In the embodiment shown and described, the second coil 19 a and thesecond coil 19 c that are arranged diametrically symmetrically areconnected in series. In addition, the second coil 19 a and the secondcoil 19 c are wound in the respective directions opposite to each otheras they are viewed from the outer circumferential direction. Similarly,the second coil 19 b and the second coil 19 d that are arrangeddiametrically symmetrically are connected in series. In addition, thesecond coil 19 b and the second coil 19 d are wound from the directionsopposite to each other as they are viewed in the outer circumferentialdirection.

Each of the second coils 19 a to 19 d has its rectangular front sideedge 21 (FIG. 2) that is placed over the outer circumferential surfaceof the front side portion 16 a of the first coil 16 (FIG. 3).Furthermore, each of them has its rear side edge 23 (FIG. 2) that isplaced over the outer circumferential surface of the rear side portion16 b of the first coil 16 (FIG. 3).

Each of the second coils 19 a to 19 d has a ring-like hollow into whichthe projections 5 a of the lens support 5 can be inserted. In this way,each of the second coils 19 a to 19 d can be held securely andpositioned accurately.

As shown in FIG. 2, the lens driving device may be assembled and mountedin the following manner. That is, the rear side spring 11, the rear sidespacer 15, the lens support 5 with the first coil 16 and the secondcoils 19 a to 19 d fixed to the outer circumferential surface, the yoke3 with the four magnets 17 fixed to the inner side of each of thecorners, the front side spacer 14, the front side spring 9 and the frame7 can be assembled together and fixed to the base 8 in the sequence ofthe parts or elements listed above. The lens driving device will thus becompleted as shown in FIG. 3.

In the state in which the lens driving device has been completed asshown in FIG. 3, the outer circumferential portion 9 a of the front sidespring 9 will be held securely between the frame 7 and the front sidespacer 14, and the inner circumferential portion 9 b will be fixed tothe front end of the lens support 5. The outer circumferential portion11 a of the rear side spring 11 will be held securely between the base 8and the rear side spacer 15, and the inner circumferential portion 11 bmay be fixed to the rear end of the lens support 5. In this way, thelens support 5 will be supported by the front side spring 9 and the rearside spring 11 so that it can be moved freely in the forward andbackward directions (in the optical axis direction).

In the state in which the lens driving device has been completed asshown in FIG. 3, the inner circumferential side of each of the frontside magnets 17 a will be located so that it can face opposite the outercircumferential side of the front side edge 21 of each of thecorresponding second coils 19 a to 19 d. Thus, the inner circumferentialside of each of the front side magnets 17 a will be located so that itcan also face opposite the outer circumferential side of the front sideportion 16 a of the first coil 16 by holding the front side edge 21securely therebetween.

In the state in which the lens driving device has been completed asshown in FIG. 3, the inner circumferential side of each of the rear sidemagnets 17 b will also be located so that it can face opposite the outercircumferential side of the rear side edge 23 of each of thecorresponding second coils 19 a to 19 d. Thus, the inner circumferentialside of each of the rear side magnets 17 b will be located so that itcan also face opposite the outer circumferential side of the rear sideportion 16 b of the first coil 16 by holding the rear side edge 23securely therebetween.

The first coil 16 and each of the second coils 19 a to 19 d have therespective input terminal and output terminal which are connected to acontrol portion 25 disposed inside the autofocus camera as shown in FIG.4.

The control portion 25 is connected to the image sensor 31. The imagesensor 31 is disposed on the image forming side of the lens (on the rearside in FIG. 3), and may be operated to receive light from anyparticular object and convert the light into corresponding electricalsignals. The control portion 25 provides the functions for controllingthe direct currents separately from each other so that those directcurrents can flow through the first coil 16 and each of the second coils19 a to 19 d. The control portion 25 includes a movement control 27 anda tilt correction control 29. The movement control 27 allows thelater-described lens support 5 to be moved, and the tilt correctioncontrol 29 allows any tilt that may occur in the optical axis of thelens to be corrected as appropriate.

For example, the control portion 25 may be operated to apply force tothe lens support 5 so that it can be moved in the optical axis direction(Z-axis direction), by flowing currents through the front side portion16 a and rear side portion 16 b in the respective directions opposed toeach other. In this way, the force for moving the lens support 5 in thedirection A in FIG. 4 will be applied to the lens support 5 so that itcan be moved forwardly up to the focal point position.

In addition, the control portion 25 may be operated to control thecurrents to be supplied to the second coil 19 b and the second coil 19 darranged diametrically symmetrically and connected in series so that thecurrents can flow through those coils in the respective directionsopposite to each other as they are viewed from the outer circumferentialdirection. In this way, the force will be produced so that it can allowthe lens support 5 to be moved in the direction of arrow B in FIG. 4.Specifically, it will allow one end of the lens support 5 to be raisedand the other end to be lowered. Any tilt will thus be corrected.

Similarly, the control portion 25 may be operated to control thecurrents to be supplied to the second coil 19 a and the second coil 19 carranged diametrically symmetrically and connected in series so that thecurrents can flow through those coils in the respective directionsopposite to each other as they are viewed from the outer circumferentialdirection. In this way, the force will be produced so that it can allowthe lens support 5 to be moved in the direction of the arrow B in FIG.4. Specifically, it will allow one end of the lens support 5 to beraised and the other end to be lowered. Any tilt will thus be corrected.

It may be understood from the above description that the control portion25 provides the functions for receiving electrical signals from theimage sensor 31 and for permitting the lens driving device 1 to respondto the electrical signals for correcting any tilt that may occur in theoptical axis of the lens (not shown) fixed to the inner circumferentialside of the lens support 5.

Any tilts of the optical axis of lens with respect to the image sensor31 in the orthogonal directions with each other can be correctedaccordingly.

Specifically, the control portion 25 may be operated to cause the lensdriving device 1 to adjust any tilt that may occur in the optical axisof the lens (not shown) fixed to the inner circumferential side of thelens support 5, by controlling the values and directions of currentflowing through the second coils 19 a and 19 c arranged diametricallysymmetrically and through the second coils 19 b and 19 c arrangedsymmetrically in the direction orthogonal to the second coils 19 a and19 c. Thus, the control portion 25 can be operated to adjust any tiltsof the optical axis of lens with respect to the image sensor 31 in theorthogonal directions with each other.

Either of the second coil 19 b and the second coil 19 d will be raisedand the other will be lowered. Thus, the lens support 5, which has beencaused by the first coil 16 to move up to the focal point position willremain in the focal point position without being moved away from thatfocal point position.

Referring to FIG. 5 through FIG. 7, another form of the lens drivingdevice, which is different from the lens driving device described abovein FIG. 2 through FIG. 4 and can be used with the camera of the presentinvention, will be described below.

The lens driving device shown in FIG. 5 through FIG. 7 differs from thelens driving device shown and described in FIG. 2 through FIG. 4 in thatit does not include the first coil 16.

Other parts or elements are similar to those for the lens driving devicein FIG. 2 through FIG. 4. Those parts or elements which are common tothose for the lens driving device in FIG. 2 through FIG. 4 are givenlike reference numerals and will not described therefore.

It should be noted that each of the second coils 19 a to 19 d in thelens driving device shown in FIG. 2 through FIG. 4 are woundindependently of each other.

By enabling the control portion 25 to control the currents so that thesame amount of current can flow through each of the second coils 19 a to19 d, for example, the force that occurs in the optical axis directionas indicated by the arrow A in FIG. 7 will be applied to the lenssupport 5. In this way, the force that occurs in the direction asindicated by the arrow A in FIG. 7 will actually be applied to the lenssupport 5 so that the lens support 5 can be moved forwardly until itreaches the focal point position parallel with the image sensor 31.

Actually, there are different types of errors that may cause the tilt tooccur. In this situation, therefore, the lens support 5 will not bemoved in parallel with the image sensor 31 if no tilt is caused by sucherrors. That is, the lens support 5 will remain the same position.

If any tilt is caused by some errors, the tilt correction will beperformed as described below.

When a large amount of current is flowed through the second coil 19 conly, for example, the second coil 19 c only will try to move largely asshown by the arrow B in addition to the movement as shown by the arrow Aand described above. In this way, one end of the lens support 5 will beraised, and then the tilt correction will be performed.

Alternatively, the magnitude of the current flowing through the secondcoils 19 b and 19 d arranged diametrically symmetrically may bedifferent from the magnitude of the current flowing through the secondcoils 19 a and 19 c arranged in the position that is orthogonal to thesecond coils 19 b and 19 d. For example, the magnitude of the currentflowing through the second coil 19 a may be smaller than the magnitudeof the current flowing through the second coils 19 b and 19 d, and themagnitude of the current flowing through the second coil 19 c may belarger than the magnitude of the current flowing through the secondcoils 19 b and 19 d. Even in this situation, one end of the lens support5 will be raised and the other end will be lowered, the tilt correctionwill thus be performed.

For the lens driving device shown in FIG. 5 through FIG. 7, the controlportion 25 may also be operated so that any tilts of the optical axis oflens with respect to the image sensor 31 in the orthogonal directionswith each other can be corrected.

FIG. 1 is a concept diagram that is used for explaining the tiltdetecting mechanism employed by the present invention.

It is supposed that the lights A to E received from a particular frontobject and the lights V to Z received from another particular objectthat is located obliquely with respect to the front object will enterthe image sensor 31 through the lens so that the image sensor 31 canconvert those lights into corresponding electrical signals in responseto those lights. It is also supposed that each of those lights A to Eand V to Z will enter the lens at equal intervals.

In FIG. 1( a), it is supposed that the lens is placed in parallel withthe image sensor 31 and is spaced away from the image sensor 31 by thedistance of L. It is also supposed that the distance of L represents thefocal point.

In FIG. 1( b), it is supposed that the lens is inclined with respect tothe image sensor 31 and that the distances between each position of thelens through which the lights can enter the image sensor 31 and theimage sensor 31 are equal to L−2Δ, L−Δ, L, L+Δ, and L+2Δ, respectively.

The lights A to E from the front object will pass through each of thecorresponding points of the lens, and will be focused upon theparticular points on the image sensor 31. The lights V to Z from theobject located obliquely with respect to the front object will passthrough each of the corresponding points of the lens, and will befocused upon the different points on the image sensor 31. Thus, thelights that enter the image sensor 31 represent the sum of the lightsthat enter the image sensor 31 from each of those points of the lens.

Here, the resolution signals thus obtained may be used as a parameterthat allows any lens tilt to be determined. The resolution signal is thesignal that indicates the degree of the focal point which may beexpressed in terms of the contrast value in the high tone range and thelike, for example. For the simplicity of explanation, it is supposedthat the resolution signal may be determined by the distance between thelens and the image sensor 31.

In FIG. 1( a), it is assumed that the resolution signal has themagnitude of “5”, for example, when the light C is received from a frontobject. Because the lens and the image sensor 31 are kept in parallelwith each other, the corresponding resolution signals also have themagnitude of “5” when other lights A, B, D and E are received from thesame front object. This means that the corresponding resolution signalswill also have the magnitude of “5” when those lights A to E are summedup.

Similarly, it is assumed that the resolution signal also has themagnitude of “5” when a light X is received from an object locatedobliquely with respect to the front object, since the distance betweenthe lens and the image sensor 31 is L. The corresponding resolutionsignals will also have the magnitude of “5” when other lights V, W, Yand Z are received from the same object located obliquely with respectto the front object.

As described above, the resolution signal has the magnitude of “5” whenthe light C is received from the front object, since the distancebetween the lens and the image sensor 31 is L. In FIG. 1( b), however,the corresponding resolution signals will have the magnitude of “4” and“3”, for example, when the light B and the light A are received, sincethe respective distances between the lens and the image sensor 31 becomesmaller such as L−Δ and L−2Δ. Similarly, the corresponding resolutionsignals will have the magnitude of “4” and “3”, for example, when thelight D and the light E are received, since the respective distancesbetween the lens and the image sensor 31 become greater such as L+Δ andL+2Δ. It follows from the above that the corresponding resolutionsignals can have the magnitude of “4” when the lights A to E arereceived from the front object.

It may be appreciated from FIG. 1( b) that the corresponding resolutionsignals will also have the magnitude of “4” when the lights V to Z arereceived from the object located obliquely with respect to the frontobject. This means that if there is any tilt in the optical axis of thelens, the corresponding resolution signals may have the magnitude thatdepends on the degree of any tilt that may occur. It can be said,therefore, that the magnitude of the resulting resolution signals maybecome smaller regardless of the location of the image sensor 31.

For the case of FIG. 1( a), the corresponding respective resolutionsignals for the lights in the center area (one area) and the peripheralareas (eight areas) on the image sensor 31 will have the maximummagnitude of “5”.

For the case of FIG. 1( b), on the other hand, the correspondingrespective resolution signals for the lights in the center area (onearea) and the peripheral areas (eight areas) on the image sensor 31 willhave the magnitude of “4”, which means that the magnitude will becomesmaller than the maximum value of “5”.

Then, considering the magnitude of the resolution signal for the lightin the particular one point on the image sensor 31 without consideringthe direction of any tilts of the optical axis of lens with respect tothe image sensor 31, the tilt correction may be performed under controlof the control portion 25 so that the maximal resolution signal thatoccurs at the particular one point can be obtained.

The particular one point to be noted can be the center area on the imagesensor 31 which may be represented as the “focal point adjusting region”as shown in FIG. 10( a), for example. Alternatively, it may be thecenter area of the image sensor 31 which is represented as the “focalpoint adjusting region” in FIG. 10( c) or any one of the peripheralareas of the image sensor 31 that surround the center area of the imagesensor 31 as shown.

Alternatively, the resolution signals that may be obtained at the fiveareas represented as the “focal point adjusting region” as shown in FIG.10( c) may be averaged by the control portion 25, and the tiltcorrection may occur under control of the control portion 25 asdescribed above so that the resulting average value can be maximized.

Following the step in which the control portion 25 is operated tocontrol so that the resolution signal that occurs at the particular onepoint on the image sensor 31 can be maximized as described above, thehuman face will be recognized and if the tilt correction is required, itwill be performed by the control portion 25 so that the resolutionsignal can be obtained at the location of the image sensor 31 thatcorresponds to the location of the recognized human face.

In accordance with the autofocus camera of the present invention, anytilt that may occur in the optical axis of the lens with respect to theimage sensor 31 can be adjusted by using the resolution signals(focusing signals) that can be obtained at the particular locations ofthe image sensor 31. There is no need of adding any additional newsensors that may be required for restraining and correcting such tilt.From this respect, therefore, the present invention can meet therequirements of making the autofocus camera as small as possible.

As the autofocus camera of the present invention can be made smaller,the electronic devises such as mobile phones, multi-function mobilephones and the like on which the autofocus camera of the presentinvention is mounted can also be made smaller accordingly.

In the embodiment shown and described above, the lens driving device 1is used for the VCM. Alternatively, the lens driving device 1 may beused for other driving motors such as the driving motor using thepiezoelectric element.

In the lens driving device 1 shown in FIG. 2 through FIG. 4, it ispreferred that the second coils 19 a to 19 d are connected to thecontrol portion 25 independently of each other and that currents areflowed through those second coils separately from each other.

The following description, which will be provided by referring to FIG. 8and FIG. 9, concerns the embodiment in which the tilt correction occursfor the autofocus camera of the present invention on which the lensdriving device 1 shown in FIG. 2 through FIG. 4 is mounted.

It should be understood that the present invention is not limited to theembodiment shown and described above as well as the embodiment that willbe described below. Rather, the present invention may be modified innumerous ways without departing from the spirit and scope of theinvention as defined in the appended claims.

Embodiment

As a preliminary step, the control portion 25 is operated to control thelens support 5 so that the lens support 5 can be moved to theappropriate focal point position by conducting electric currents to flowthrough the first coil 16. Then, the control portion 25 proceeds to thestep in which the second coils 19 a,19 c, for example, are selected fromthe second coils 19 a, 19 c and the second coils 19 b, 19 d arrangedorthogonally to each other, and the adjustment by those second coils 19a, 19 c is commenced (the θx direction is supposed) (S801).

Firstly, a resolution signal X1 in the center area of the image sensor31 is obtained (S802).

Next, the second coils 19 a, 19 c that have been selected are energizedso that the lens support 5 can be moved in the direction of +θx (therebythe lens support 5 is to be tilted) (S803) and a resolution signal X2 inthe center area of the image sensor 31 can be obtained at the positionwhere the lens support 5 has been moved (S804).

The resolution signal X1 and the resolution signal X2 are compared(S805). If X1<X2, it is determined that the two resolution signals agreewith each other in the direction of +θx so that the lens support 5 iscontinued to move in the direction +θx (thereby the lens support 5 iscontinued to tilt further). At the first, the resolution signal X2,which was obtained at step S804, is replaced with a resolution signal X3by the process conducted by the control portion 25 (S806), then, thelens support 5 is moved in the direction of +θx (S807), and a resolutionsignal X4 in the center area of the image sensor 31 is obtained at theposition where the lens support 5 has been moved (S808).

Then, the resolution signal X3 and the resolution signal X4 are compared(S809).

If X3<X4, the resolution signal X4 is replaced with the resolutionsignal X3 by the process conducted by the control portion 25 (S810), andthen, the lens support 5 is continued to move further in the directionof +θx again (S807), the resolution signal X4 in the center area of theimage sensor 31 is obtained again at the position where the lens support5 has been moved (S808), and the resolution signal X3 and the resolutionsignal X4 are compared again (S809).

If X3>X4, this means that the resolution signals have passed the peak sothat the lens support 5 is moved in the direction −θx and is moved backto the position where the resolution signal X3 has been obtained, whichis the position that the resolution signal X4 was obtained at the beforedescribed step S808 (S811).

This also means that the resolution signal X3, which is the resolutionsignal obtained at the before described step S808 as the resolutionsignal X4, represents the maximum resolution signal so that the lenssupport 5 is moved back to the position where the resolution signal X3,which is the resolution signal obtained at the before described stepS808 as the resolution signal X4, has been obtained. Then, the movementof the lens support 5 in the direction of θx is finished (S818).

In the manner described above, the lens support 5 will be moved in thedirection of θx up to the position where the maximum resolution signalcan be obtained.

If it is found by comparing the resolution signals X1 and X2 that X1<X2,the lens support 5 will be moved in the direction of +θx, which meansthat the magnitude of the resolution signal will become smaller. Thisalso means that the lens support 5 must be moved backwardly in thedirection of −θx so that the lens support 5 must be tilted towardopposite direction which the lens support 5 is tilted by the moving ofthe lens support 5 in the direction of +θx .

After the resolution signals X1 and X2 have been compared in the abovecase, the resolution signal X2 is replaced with the resolution signal X5by the process conducted by the control portion 25 (S812), the lenssupport 5 is moved in the direction of −θx (S813), and the resolutionsignal X6 in the center area of the image sensor 31 is obtained at theposition where the lens support 5 has been moved (S814).

Then, the resolution signals X5 and X6 are compared (S815).

If it is found by comparing the resolution signals X5 and X6 (S815) thatX5<X6, the resolution signal X6 is replaced with the resolution signalX5 by the process conducted by the control portion 25 (S816), the lenssupport 5 is moved further in the direction of −θx again (S813), theresolution signal X6 in the center area of the image sensor 31 isobtained at the position where the lens support 5 has been moved (S814),and the resolution signals X5 and X6 are compared (S815).

If X5>X6, this means that the resolution signals have passed the peak sothat the lens support 5 is moved in the direction +θx and is then movedback to the position where the resolution signal X5, which is theresolution signal obtained at the before described step S814 as theresolution signal X6, has been obtained.

This also means that the resolution signal X5, which is the resolutionsignal obtained at the before described step S814 as the resolutionsignal X6, represents the maximum resolution signal and so the lenssupport 5 is moved back to the position where the maximum resolutionsignal has been obtained. The movement of the lens support 5 in thedirection of θx is then finished (S818).

In the manner described above, the lens support 5 is moved in thedirection of θx until it reaches the position where the maximumresolution signal can be obtained.

Next, the control portion 25 goes to the step in which the second coils19 b, 19 d, for example, are selected from the second coils 19 a, 19 cand the second coils 19 b, 19 d arranged orthogonally to each other, andthe adjustment by those second coils 19 b, 19 d is commenced (the θydirection is supposed) (S819)

Firstly, the resolution signal Y1 in the center area of the image sensor31 is obtained (S820).

Next, electric currents are conducted to flow through the second coils19 b, 19 d so that the lens support 5 can be moved in the direction of+θy (thereby the lens support 5 is to be tilted) (S821), and theresolution signal Y2 in the center area of the image sensor 31 isobtained at the position where the lens support 5 has been moved (S822).

If it is found by comparing the resolution signals Y1 and Y2 (S823) thatY1<Y2, it is determined that those resolution signals agree with eachother in the +θy direction and so the lens support 5 is continued tomove in the direction (thereby the lens support 5 is continued to tiltfurther). Firstly, the resolution signal Y2, which was obtained at stepS822, is replaced with a resolution signal Y3 by the process conductedthe control portion 25 (S824), the lens support 5 is moved in thedirection of +θy (S825), and the resolution signal Y4 in the center areaof the image sensor 31 is obtained at the position where the lenssupport 5 has been moved (S826).

Then, the resolution signals Y3 and Y4 are compared (S827).

If Y3<Y4, the resolution signal Y4, which was obtained at step S826, isreplaced with a resolution signal Y3 by the process conducted by thecontrol portion 25 (S828), the lens support 5 is moved further in thedirection of +θy again (S825), the resolution signal Y4 in the centerarea of the image sensor 31 is obtained at the position where the lenssupport 5 has been moved (S826), and the resolution signals Y3 and Y4are compared (S827).

If Y3>Y4, this means that the resolution signal has passed its peak sothat the lens support 5 is moved in the direction of −θy and is thenmoved back to the position where the resolution signal Y3, which is theresolution signal obtained at the before described step S826 as theresolution signal Y4, has been obtained (S829).

This also means that the resolution signal Y3, which is the resolutionsignal obtained at the before described step S826 as the resolutionsignal Y4, represents the maximum resolution signal and so the lenssupport 5 is moved back to that position. The movement of the lenssupport 5 in the direction of θy is then finished (S836).

In the manner described above, the lens support 5 will be moved in thedirection of θy until it reaches the position where the maximumresolution signal can be obtained.

If it is found by comparing the resolution signals Y1 and Y2 that Y1>Y2,on the other hand, this means that the lens support 5 is moved in thedirection of +θy, causing the magnitude of the resolution signal to havebecome smaller. Therefore, the lens support 5 must be moved backwardlyin the direction −θy so that the lens support 5 must be tilted towardopposite direction which the lens support 5 is tilted by the moving ofthe lens support 5 in the direction of +θy.

After the resolution signals Y1 and Y2 have been compared in the abovesituation, the resolution signal Y2 is replaced with the resolutionsignal Y5 by the process conducted by the control portion 25 (S830), thelens support 5 is moved in the direction of −θy (S831), and theresolution signal Y6 in the center area of the image sensor 31 isobtained at the position where the lens support 5 has been moved (S832).

Then, the resolution signals Y5 and Y6 are compared (S833).

If it is found by comparing the resolution signals Y5 and Y6 that Y5<Y6,the resolution signal Y6 is replaced with the resolution signal Y5 bythe process conducted by the control portion 25 (S834), the lens support5 is moved further in the direction of −θy again (S831), the resolutionsignal Y6 in the center area of the image sensor 31 is obtained at theposition where the lens support 5 has been moved (S832), and theresolution signals Y5 and Y6 are compared (S833).

If Y5>Y6, this means that the resolution signal has passed its peak,causing the lens support 5 to be moved in the direction of +θy so thatit can be moved back to the position where the resolution signal Y5,which is the resolution signal obtained at the before described stepS832 as the resolution signal Y6, has been obtained.

This means that the resolution signal Y5, which is the resolution signalobtained at the before described step S832 as the resolution signal Y6,represents the maximum resolution signal, and the lens support 5 ismoved back to that position. The movement of the lens support 5 in thedirection of θy is then finished (S836).

In the manner described above, the lens support 5 is moved in thedirection of θy until it reaches the position where the maximumresolution signal can be obtained.

It may be understood from the foregoing description that the controlportion 25 may correct any tilts of the optical axis with respect to theimage sensor 31 in the directions of θx and θy, orthogonal directionwith each other so that the resolution signal in the center area of theimage sensor 31 can be maximized.

Although the resolution signals that occur in the center area of theimage sensor 31 are referenced and controlled by the control portion 25in accordance with the embodiment described above, it should beappreciated that resolutions signals that may occur in other areas suchas the peripheral areas of the image sensor 31 may also be referencedand controlled by the control portion 25.

1. An autofocus camera comprising: an image sensor for receiving lightfrom an object and converting the light into corresponding electricalsignals; a lens driving device having a lens for focusing the light fromthe object upon said image sensor; and a control portion for causingsaid lens driving device to adjust any tilt that may occur in theoptical axis in response to the electrical signals received from saidimage sensor, wherein said control portion is operated to cause saidlens driving device to adjust any tilts of the optical axis with respectto the image sensor in the orthogonal directions with each other, sothat the resolution signals at the predetermined positions of said imagesensor can be maximized.
 2. The autofocus camera as defined in claim 1,wherein said resolution signals are derived from either of thecenter'area of said image sensor and the peripheral areas of said imagesensor.
 3. The autofocus camera as defined in claim 1, wherein saidcontrol portion is operated to determine an average value obtained byaveraging said resolution signals obtained at more than one point ofsaid image sensor and adjust any tilts of the optical axis with respectto the image sensor in the orthogonal directions with each other, sothat said average value can be maximized.
 4. An electronic device onwhich the autofocus camera as defined in claim 1 is mounted.
 5. Anelectronic device on which the autofocus camera as defined in claim 2 ismounted.
 6. An electronic device on which the autofocus camera asdefined in claim 3 is mounted.